This invention relates to a plate-type printing device and a method of using same. More particularly, this invention relates to a plate-type multicolor printing device capable of printing a multicolored design in a single impression step.
Multicolor printing devices are known in the art. Reference is made, for example, to U.S. Pat. Nos. 2,864,310 to Nelson; 2,132,086 to Scheffler; and 4,516,496 to Giori.
A major drawback to conventional multicolor printing devices such as those disclosed in the foregoing references is that these devices require a separate plate or cylinder for each color to be supplied to an inking surface. The use of a separate plate or cylinder for each color tends to make these conventional printing devices relatively expensive and time-consuming to make, clean, re-use and/or replace. It would be desirable, therefore, to provide a multicolor printing device which does not require a separate plate or cylinder for each color to be supplied. It would be particularly desirable to provide a multicolor printing device which is relatively compact in design.
Another drawback to many conventional printing devices such as those disclosed in the Scheffler and Giori patents cited hereinabove is that ink is fed to the inking surface from a direction above or in front of the inking surface. In such an ink supply arrangement, ink replenishment of the inking surface generally requires manually and separately bringing each ink supply source in contact with the inking surface to transfer ink from the supply source to the inking surface. Such a step can be time-consuming and tends to make the printing system costlier and more complicated. Furthermore, the use of a plurality of separate ink supply sources and an inking source results in an undesirably bulky printing system. It would be desirable, therefore, to provide a printing device wherein ink can be continuously supplied to the inking surface. It would further be desirable to provide a relatively compact printing device wherein the ink supply source is composed of a single structure disposed to provide continuous ink replenishment to the inking surface.
The Nelson patent, cited hereinabove, discloses a printing device in which ink is fed to the inking surface from below, wherein the inking surface is disposed on an upper edge surface of a plate and the ink-supply source is disposed near the bottom edge of the plate. However, the Nelson printing device has a number of significant drawbacks.
For example, as mentioned previously herein, Nelson requires a separate plate for each color to be printed. The inking surface in the Nelson printing device is not divided into sections for different colored inks. For reasons given previously herein, it would be desirable to provide a printing device which does not require a separate plate for each color to be supplied.
In addition, in the Nelson printing device and method, ink is supplied to the inking surface by means of a relatively complicated labyrinth of channels, ducts, notches and holes. It would be desirable to provide a printing device wherein ink is supplied to the inking surface by means of a relatively simple channel arrangement.
In Nelson, the inking surface is disposed on an edge of a plate and is composed of a plurality of slots through which ink reaches the inking surface. Nelson teaches that the depth and width of these slots will determine the amount of color which is carried to the inking surface. Because the inking surface in Nelson is disposed on a plate edge, the width of these slots (and, consequently, the amount of ink reaching the inking surface) is limited by the thickness of the plate. In other words, the thinner the plate, the more narrow the slots on the inking surface (plate edge) and the less ink which can reach the inking surface. However, where a plate edge serves an the inking surface, the use of thicker plates also has drawbacks. For example, thicker plates limit the resolution of the image obtained because the thickness of the plates will define the minimum separation of pixels. The thicker the plates, the greater the distance between pixels and the lower the image resolution achieved. In addition, thick plates are more expensive to make and replace than are thin plates. Thick plates also result in a bulkier structure than do thin plates. Bulkier structures are generally more expensive and time-consuming to make, clean, inspect, re-use and/or inspect than are less bulky structures. Furthermore, thick plates are harder and more expensive to machine than are thin plates. It would be desirable, therefore, to provide a printing device wherein the amount of color reaching the inking surface is not limited by plate thickness.
In addition, it is continually desirable to provide a printing device and printing method wherein a multicolored print can be formed in a single impression with a single inking surface. Printing processes requiring more than one impression step have numerous drawbacks including, e.g., long drying periods between impression steps, differences in color register, waste of paper and other printed articles, waste of ink due to misprints, and reduced image sharpness of the first printed design.
A primary object of this invention is to provide a plate-type single-impression, multicolor printing device wherein ink is continuously fed to the inking surface from the back or bottom of the inking surface.
Another object of the present invention is to provide a plate-type single-impression, multicolor printing device wherein a single plate can supply a plurality of colored liquids to an inking surface.
A further object of the present invention is to provide a plate-type single-impression, multicolor printing device wherein a single surface of a single plate can supply a plurality of colored liquids to an inking surface.
A still further object of this invention is to provide a plate-type single-impression, multicolor printing device wherein a single plate can receive and be used to transfer a plurality of colored liquids.
Another object of this invention is to provide a plate-type single-impression, multicolor printing device wherein a single surface of a single plate can receive and be used to transfer a plurality of colored liquids.
A further object of this invention is to provide a plate-type single-impression, multicolor printing device wherein ink is supplied to the inking surface by means of a relatively simple channel design.
Another object of this invention is to provide a plate-type single-impression, multicolor printing device wherein the inking surface and the ink-supply source are disposed in a relatively compact structure.
A still further object of this invention is to provide a plate-type single-impression, multicolor printing device wherein the device is composed of relatively thin plates.
A further object of the present invention is to provide a method of single-impression, multicolor printing by means of a plate-type multicolor printing device having the characteristics set forth in the preceding objects.
These and other objects which are achieved according to the present invention can be readily discerned from the following description.